Two silent substitutions in the PDHA1 gene cause exon 5 skipping by disruption of a putative exonic splicing enhancer.

BACKGROUND: Synonymous mutations within exons may cause aberrant splicing by disrupting exonic splicing enhancer (ESE) motifs in the vicinity of non consensus splice sites. Mutational analysis of PDHA1 revealed only one silent single nucleotide substitution in exon 5 in two unrelated boys and a girl (c.483C>T and c.498C>T variants, respectively). For both patients, pyruvate dehydrogenase complex activity was low and the immunoreactive E1alpha protein was defective in cultured fibroblasts. METHODS AND RESULTS: One of the boys was a somatic mosaic for the c.483C>T variant, as shown by the variable ratio of mutant to normal alleles in fibroblast, lymphocyte and single hair root DNA. Transcript analysis in fibroblasts from the three patients revealed the presence of both normal and truncated cDNAs, with the splicing out of exon 5 predicted to result in a frame shift and premature termination (p.Arg141AlafsX11). The treatment of fibroblasts with emetine before harvesting to prevent nonsense mRNA-mediated decay increased the amount of mutant mRNA. In silico analysis revealed that each variant disrupted a putative SRp55 binding site and that the intron 5 donor splice site (5'ss) contained a weak splicing signal. Transient transfection of COS-7 or Hela cells with hybrid minigene constructs containing wild-type or mutant PDHA1 exon 5, followed by RT-PCR demonstrated that each variant resulted in the incomplete inclusion of PDHA1 exon 5, and that this defect was corrected following the restoration of a perfect consensus sequence for the 5' splice site by site-directed mutagenesis. CONCLUSION: These two synonymous mutations expand the spectrum of rare PDHA1 splicing mutations, all of which are located in non canonical splice sites.

Prognostic factors in patients undergoing curative irradiation for breast cancer.

We have evaluated 147 patients who received primary curative irradiation for breast cancer to determine if there were any common factors that predisposed to failure. There were 10 local recurrences, for an overall local control rate of 93.2%, with a 2 to 16 year follow-up. Disease-free survivals were 85% in Stage I, 69% in Stage II, and 50% in Stage III. Age seemed to be a determinant, with a 31.6% local recurrence rate in women under 50 vs. a 3.1% rate of local recurrence in women age 50 or older when treated. We have also noted a correlation between the radiation dose and local recurrence, with a recurrence rate of 9.1% following a dose of 6000 rad or less, vs. a rate of 4.7% with a dose of 6400 rad or more. The size of the primary carcinoma and the status of the axillary lymph nodes, each considered individually, were not significant prognostic factors. There was no relationship between recurrence and the performance of an axillary dissection. There was evidence suggesting that the recurrence rate was lower when a wide local excision was performed, compared to a lesser procedure. Multiple foci of carcinoma and a high nuclear grade appear to have a poor prognosis. Five of the recurrences occurred early (under 2 years) and three of these were accompanied by fatal distant metastases. None of the five patients with late recurrences (37 to 116 months) developed metastatic disease, suggesting that late recurrences may have a better prognosis.

Selection, follow-up, and analysis in the Health Insurance Plan Study: a randomized trial with breast cancer screening.

Critical decisions made 20 years ago by those who planned the randomized trial at the Health Insurance Plan (HIP) of Greater New York to determine the efficacy of periodic screening for breast cancer are detailed. These decisions affected the age group to be screened, screening modalities, frequency of screening, sample size, primary measures for testing efficacy, and period of follow-up (long term). Results of follow-up, 16 years after entry, indicate that mortality due to breast cancer continues to be lower among study women than controls. Numerically, the differential has been stable; relatively, it has decreased. It is estimated that the study group would have experienced about a 30% reduction in breast cancer mortality if screening had been maintained. Relative case survival rates over a 14-year period after diagnosis show changes in contours of trend lines that result from screening. The study group's trend is slightly concave in contrast to the usual convex curve for the controls. The contour of the curve is more decidedly concave among subjects detected through mammography alone than for other subgroups detected through screening, although the relative survival rate remains highest in the mammography only group. Uncertainty persists about effects of screening in the HIP study on breast cancer mortality among women aged 40-49 years at entry.

Carcinoma of the breast: interrelationships among histopathologic features, estrogen receptor activity, and age of the patient.

Of 398 cases of breast cancer, 350 included data for all of the following: patient age, tumor size, histologic type, presence or absence of lymph node metastasis, nuclear grade of the cancer cells, extent of lymphocytic infiltration around these cells, and estrogen receptor status of the neoplastic tissue. This series is representative of and comparable with those reported in other studies of breast carcinoma. Initial evaluation suggested a relationship of cytologic differentiation and lymphocytic infiltration to estrogen receptor activity. More extensive statistical analyses, however, demonstrated that three factor interrelationships best explain the data concerning nuclear grade, lymphocytic infiltration, and estrogen receptor activity of the tumors in this study. Thus, the results of this investigation serve to warn against inferential judgments based on limited data or restricted evaluation. In addition, the analyses call attention to a significant association between age and lymphocytic infiltration around the tumor cells.

Prospects for eliminating racial differences in breast cancer survival rates.

Results from the randomized trial underway in the Health Insurance Plan of Greater New York to determine the efficacy of periodic screening with mammography and palpation of the breast have been examined to determine the effect of screening on racial differences in breast cancer survival rates. Consistent with experience in general populations, the control group showed a lower five-year survival rate among non-White women with breast cancer than among White women. In the study group, 65 per cent of whom participated in the screening program, there was no differential in the survival rates of the two racial groups. The elimination of the unfavorable status among non-Whites through screening does not appear to be explained by various artifacts explored. Secondary prevention measures may offer the possibility of reducing or closing the gap in breast cancer survival rates between White and non-White women.

Ten- to fourteen-year effect of screening on breast cancer mortality.

Results from the randomized trial conducted by the Health Insurance Plan (HIP) to determine the efficacy of breast cancer screening with mammography and palpation are reported for longer periods than previously available. By the end of 10 years after entry, the study group's mortality due to breast cancer was about 30% below the control group's. Arithmetic gains due to screening were maintained through year 14; relative gains declined. With increases in the period of follow-up, cumulative survival rates among cases detected by mammography alone (palpation negative during screening), decreased more rapidly than rates among other subgroups, but survival rates for mammography cases remained relatively high. Study women aged 40-49 years at entry began to show lower breast cancer mortality than those in the control group as duration of follow-up increased. Reservations are advanced about the acceptance of this finding as evidence of the efficacy of screening under age 50 under the conditions of the HIP study. The reservations are based on the observation that the decrease of mortality among the study group aged 45-49 at entry is concentrated entirely among cases diagnosed after they reached 50 years of age.

Self-examination and clinical examination of the breast.

The techniques of self breast examination and the clinical examination of the breasts are described briefly. The potential value and the limitations of these tests in screening for breast cancer are reviewed. In a Cancer Society Monograph in 1958, Haagensen said, "It is probable that, from the point of view of the greatest possible gain in early diagnosis, teaching women how to examine their own breasts is more important than teaching the technique of breast examination to physicians, for we must keep in mind the fact that at least 98 percent of the women who develop breast carcinoma discover their tumors themselves." Unfortunately, this is still true today. There is urgent need to focus research on methods to detect breast cancer in its early stages. Caution is emphasized in widespread advocacy of breast self examination without adequate supporting evidence of its efficacy. There is need for a well-designed, prospective study of breast self examination with full attention to a rigorous research design and methodology.

Effects of news events on response to a breast cancer screening program.

An opportunity to examine the effects of significant, widely reported events on participation in a breast cancer screening program was presented when countrywide public attention was called to breast cancer by reports of the breast surgery of the wives of President and Vice President of United States. These events occurred in September and October 1974 while a breast cancer screening program was underway in the health Insurance Plan of Greater New York. The research design of this program permitted measurements to be made of the participation of the plan's members in the screening before, during, and after these famous mastectomies and of the participants' characteristics during different periods of the research program. In late 1974, when there was great mass media emphasis on breast cancer, participation rates in the breast cancer screening program increased significantly. In the study periods immediately following, however, participation rates declined to previous levels. The increase in Participation rates in late 1974 was fairly uniform among all demographic groups, whether classified by age, education, income, race, or religion. In addition to increases in the participation rate associated with the events of late 1974, there was also an increased tendency among women who were screened to respond readily to mailed invitations to appear for screenings. This increase insensitivity to efforts to win their participation was more pronounced among those groups that this study and other studies have shown are more likely to participate in preventive health programs and to respond more readily to request to participate.